It is the purpose of this project to delineate, at the cellular and molecular levels, the mechanisms of action of microbial components in immunopotentiation. In the past year, two major efforts have been made: 1. elucidating the nature of biological response to treatment of tumors with synthetic analogs of mycobacterial cell wall components combined with endotoxic extracts obtained from Salmonella typhimurium Re mutants, and 2. establishing the structural features of analogs of adjuvant dipeptides required for antitumor activity when combined with trehalose dimycolate.